Face notches, a cutting technique used to direct the fall of a tree, have been used by humans for centuries, if not longer. When done properly, they allow users to direct and control the fall of the tree accurately and safely. In recent decades, knowledge of refined and advanced face notch techniques and their use has become available, offering arborists some different options that, in many cases, will increase the amount of control and precision they have in felling operations.
A knowledge of these techniques can assist tree care professionals in making the appropriate choice for the variety of situations and scenarios they may be confronted by in felling operations. While primarily directed toward the felling of whole trees, the use of face notches can also be advantageous in various other applications, such as lifting limbs, dropping tops during a removal, etc.; and their use in such applications should be explored and considered.
The traditional, or conventional, notch is one that many tree care professionals are familiar with; and, in all likelihood, is the face notch they received on-the-job training in at the beginning of their career and have continued to use. The traditional notch typically consists of an angled top cut of 45 degrees, a flat bottom cut, and is cut into the tree approximately one-third of its diameter. In addition, the back cut is typically stepped, or raised, 1 to 2 inches in a conventional notch, to prevent the tree from kicking backward off the stump during its fall.
Although this technique and its guidelines can appear simple and straightforward at first glance, it can often be somewhat difficult to carry out successfully and has several disadvantages in the area of control. For example, the tree is only under control as long as the hinge, the area of wood fiber behind the face notch, is functioning or bending. Once the face notch has closed, the hinge has no choice but to break, ending all control over the fall of the tree.
Assuming the tree is straight up and down, or 90 degrees in relation to the ground, the use of a 45-degree notch dictates that the face notch will have no choice but to close while it is still fairly high in the air, leaving it to travel the remaining 45 degrees of arc without control. This presents only minor problems for trees with no side lean, but the existence of even a small amount of side lean, coupled with the breaking of the hinge, means that the feller may see the tree heading in the desired direction and then taking a sudden turn in the direction of the side lean as the face notch closes and the hinge breaks.
70-degree or greater (open-face) notch
The use of a face notch with an opening of 70 degrees or more will give users a greater degree of control in felling operations. If good wood fiber is present in the hinge, the hinge will continue to function until the face notch closes, and the use of a larger opening will assure the face notch closes when the tree is much closer to the ground. A specific angle is not cited for the simple reason that individual trees grow at different angles to the ground and on a variety of slopes, thus the same degree of opening for the face notch will not suit every situation.
Climbing arborists using the open-face notch technique must determine which degree of opening is required to obtain the desired result. For example, if the tree to be felled is straight up and down on level ground, and the intended result is to keep it on the stump, than a face notch opening of greater than 90 degrees will be required. If the tree has a severe forward lean and is on level ground, then an opening of 70 degrees may be sufficient to provide maximum control until the falling tree reaches the ground. Additionally, which cuts, top or bottom, are angled is of little importance, as long as the end result is the desired degree of opening in the face notch. The top cut may be angled and the bottom cut flat, both cuts angled, or the top cut flat and the bottom cut angled (often called a Humboldt in both traditional and open-face notches). If the degree of opening is the same in all these face notches, the tree will end up in the same position relative to the ground when the face notch closes.
Users of the 70-degree or greater face notch need not worry about cutting into the tree for a specific depth, rather they should strive to expose 80 percent of the tree’s diameter from corner to corner of the face notch. Using this guideline, a 10-inch tree would require a face notch that exposes 8 inches of wood from corner to corner of the face notch, commonly called the length of hinge. The back cut when using this technique need not be stepped up as in a 45-degree notch, as the tree will have already passed through the point of maximum push-back at approximately 45 degrees with the hinge still intact, thus eliminating the possibility of kicking back off the stump.
Felling operations, face notches, back cuts, and the variety of other cutting techniques and methods available are much more complex and detailed than the information shared here, but this basic introduction to some of the advantages and disadvantages of different face notches should help tree care professionals start to examine their cutting and felling practices with an eye toward increasing control and precision. Increased control and precision can only result in safer, more efficient tree care operations.